/**
 * Copyright (C) 2002-2015   The FreeCol Team
 * <p>
 * This file is part of FreeCol.
 * <p>
 * FreeCol is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 * <p>
 * FreeCol is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * <p>
 * You should have received a copy of the GNU General Public License
 * along with FreeCol.  If not, see <http://www.gnu.org/licenses/>.
 */

package net.sf.freecol.common.networking;

import net.sf.freecol.common.model.FreeColGameObject;
import net.sf.freecol.common.model.Game;
import net.sf.freecol.common.model.Player;
import net.sf.freecol.common.model.Player.NoClaimReason;
import net.sf.freecol.common.model.Settlement;
import net.sf.freecol.common.model.Tile;
import net.sf.freecol.common.model.Unit;
import net.sf.freecol.server.FreeColServer;
import net.sf.freecol.server.model.ServerPlayer;

import org.w3c.dom.Element;


/**
 * The message sent when the client requests claiming land.
 */
public class ClaimLandMessage extends DOMMessage
{

    /** The tile to claim. */
    private final String tileId;

    /** The unit or settlement claiming the land. */
    private final String claimantId;

    /** The price to pay for the tile. */
    private final String priceString;


    /**
     * Create a new <code>ClaimLandMessage</code>.
     *
     * @param tile The <code>Tile</code> to claim.
     * @param claimant The <code>Unit</code> or <code>Settlement</code>
     *     claiming the tile.
     * @param price The price to pay for the tile, negative if stealing.
     */
    public ClaimLandMessage( Tile tile, FreeColGameObject claimant, int price )
    {
        super( getXMLElementTagName( ) );

        this.tileId = tile.getId( );
        this.claimantId = claimant.getId( );
        this.priceString = Integer.toString( price );
    }

    /**
     * Create a new <code>ClaimLandMessage</code> from a supplied element.
     *
     * @param game The <code>Game</code> this message belongs to.
     * @param element The <code>Element</code> to use to create the message.
     */
    public ClaimLandMessage( Game game, Element element )
    {
        super( getXMLElementTagName( ) );

        this.tileId = element.getAttribute( "tile" );
        this.claimantId = element.getAttribute( "claimant" );
        this.priceString = element.getAttribute( "price" );
    }


    /**
     * Handle a "claimLand"-message.
     *
     * @param server The <code>FreeColServer</code> handling the message.
     * @param player The <code>Player</code> the message applies to.
     * @param connection The <code>Connection</code> the message was from.
     *
     * @return An update, or error <code>Element</code> on failure.
     */
    public Element handle( FreeColServer server, Player player,
                           Connection connection )
    {
        final ServerPlayer serverPlayer = server.getPlayer( connection );
        final Game game = server.getGame( );

        Tile tile = game.getFreeColGameObject( tileId, Tile.class );
        if ( tile == null )
        {
            return DOMMessage.clientError( "Not a file: " + tileId );
        }

        Unit unit = null;
        try
        {
            unit = player.getOurFreeColGameObject( claimantId, Unit.class );
        }
        catch ( IllegalStateException e ) {} // Expected to fail sometimes...
        Settlement settlement = null;
        try
        {
            settlement = player.getOurFreeColGameObject( claimantId,
                                                         Settlement.class );
        }
        catch ( IllegalStateException e ) {} // ...as is this one...
        if ( unit != null )
        {
            if ( unit.getTile( ) != tile )
            {
                return DOMMessage.clientError( "Unit not at tile: " + tileId );
            }
        }
        else if ( settlement != null )
        {
            if ( settlement.getOwner( ).isEuropean( )
                    && ! settlement.getTile( ).isAdjacent( tile ) )
            {
                return DOMMessage.clientError( "Settlement can not claim tile: "
                                                       + tileId );
            }
        }
        else
        { // ...but not both of them.
            return DOMMessage.clientError( "Not a unit or settlement: "
                                                   + claimantId );
        }

        int price;
        try
        {
            price = Integer.parseInt( priceString );
        }
        catch ( NumberFormatException e )
        {
            return DOMMessage.clientError( "Bad price: " + priceString );
        }

        // Request is well formed, but there are more possibilities...
        int value = player.getLandPrice( tile );
        Player owner = tile.getOwner( );
        Settlement ownerSettlement = tile.getOwningSettlement( );
        if ( owner == null )
        { // unclaimed, always free
            price = 0;
        }
        else if ( owner == player )
        { // capture vacant colony tiles only
            if ( settlement != null && ownerSettlement != null
                    && tile.isInUse( ) )
            {
                return DOMMessage.clientError( "Can not claim tile "
                                                       + tile.getId( ) + ": already owned." );
            }
            price = 0;
        }
        else if ( owner.isEuropean( ) )
        {
            if ( tile.getOwningSettlement( ) == null  // its not "nailed down"
                    || tile.getOwningSettlement( ) == settlement )
            { // pre-attached
                price = 0;
            }
            else
            { // must fail
                return DOMMessage.clientError( "Can not claim tile "
                                                       + tile.getId( ) + ": European owners will not sell." );
            }
        }
        else
        { // natives
            NoClaimReason why = player.canClaimForSettlementReason( tile );
            switch ( why )
            {
                case NONE:
                    break; // Succeed.
                case NATIVES:
                    if ( price >= 0 )
                    {
                        if ( price < value )
                        {
                            return DOMMessage.clientError( "Can not claim tile "
                                                                   + tile.getId( ) + ": insufficient offer." );
                        }
                        if ( ! player.checkGold( price ) )
                        {
                            return DOMMessage.clientError( "Can not pay for tile: "
                                                                   + tile.getId( ) + ": insufficient funds." );
                        }
                        // Succeed, sufficient offer
                    } // else succeed, stealing
                    break;
                default: // Fail
                    return DOMMessage.clientError( "Can not claim tile "
                                                           + tile.getId( ) + ": " + why );
            }
        }

        // Proceed to claim.  Note, does not require unit, it is only
        // required for permission checking above.  Settlement is required
        // to set owning settlement.
        return server.getInGameController( )
                .claimLand( serverPlayer, tile, settlement, price );
    }

    /**
     * Convert this ClaimLandMessage to XML.
     *
     * @return The XML representation of this message.
     */
    @Override
    public Element toXMLElement( )
    {
        return createMessage( getXMLElementTagName( ),
                              "tile", tileId,
                              "claimant", claimantId,
                              "price", priceString );
    }

    /**
     * The tag name of the root element representing this object.
     *
     * @return "claimLand".
     */
    public static String getXMLElementTagName( )
    {
        return "claimLand";
    }
}
